Uses for Special Characters in Java Code
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Uses for Special Characters in Java Code
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Ever wondered how you can write code like this in Java?
It is common to see a leading underscore like _field or an underscore in a constant like UPPER_CASE. In Java the $ is also used in class names and accessor method names.
The SCJP has notes which state
And if you try the following you may find it compiles.
While this is interesting, does it have a use? Recently I found one.
I have an object which represents a column, and this column has a value for that row. The names are basically the same but I want a notation to distinguish them. So I have something like
This way I can see with is tp the column, and which is the value.
Interestingly the currency characters are valid as well.
prints
36 : $
95 : _
162 : ¢
163 : £
164 : ¤
165 : ¥
1547 : ؋
2546 : ৲
2547 : ৳
2555 : ৻
2801 : ૱
3065 : ௹
3647 : ฿
6107 : ៛
8255 : ‿
8256 : ⁀
8276 : ⁔
8352 : ₠
8353 : ₡
8354 : ₢
8355 : ₣
8356 : ₤
8357 : ₥
8358 : ₦
8359 : ₧
8360 : ₨
8361 : ₩
8362 : ₪
8363 : ₫
8364 : €
8365 : ₭
8366 : ₮
8367 : ₯
8368 : ₰
8369 : ₱
8370 : ₲
8371 : ₳
8372 : ₴
8373 : ₵
8374 : ₶
8375 : ₷
8376 : ₸
8377 : ₹
43064 : ꠸
65020 : ﷼
65075 : ︳
65076 : ︴
65101 : ﹍
65102 : ﹎
65103 : ﹏
65129 : ﹩
65284 : ＄
65343 : ＿
65504 : ￠
65505 : ￡
65509 : ￥
65510 : ￦
if( ⁀ ‿ ⁀ == ⁀ ⁔ ⁀ || ¢ + ￠== ₡)
Background
Underscores has long been using in C like language such as Java to distinguish fields and method names.It is common to see a leading underscore like _field or an underscore in a constant like UPPER_CASE. In Java the $ is also used in class names and accessor method names.
The SCJP has notes which state
Identifiers must start with a letter, a currency character ($), or a connecting character such as the underscore ( _ ). Identifiers cannot start with a number!This leads to the question; what other connecting characters are there?
What are connecting characters?
A connecting character joins two words together. This page lists ten connecting characters| U+005F | LOW LINE | _ | view |
| U+203F | UNDERTIE | ‿ | view |
| U+2040 | CHARACTER TIE | ⁀ | view |
| U+2054 | INVERTED UNDERTIE | ⁔ | view |
| U+FE33 | PRESENTATION FORM FOR VERTICAL LOW LINE | ︳ | view |
| U+FE34 | PRESENTATION FORM FOR VERTICAL WAVY LOW LINE | ︴ | view |
| U+FE4D | DASHED LOW LINE | ﹍ | view |
| U+FE4E | CENTRELINE LOW LINE | ﹎ | view |
| U+FE4F | WAVY LOW LINE | ﹏ | view |
| U+FF3F | FULLWIDTH LOW LINE | ＿ | view |
And if you try the following you may find it compiles.
int _, ‿, ⁀, ⁔, ︳, ︴, ﹍, ﹎, ﹏, ＿;
While this is interesting, does it have a use? Recently I found one.
I have an object which represents a column, and this column has a value for that row. The names are basically the same but I want a notation to distinguish them. So I have something like
Column<Double>︴tp︴ = table.getColumn("tp", double.class);
double tp = row.getDouble(︴tp︴);
This way I can see with is tp the column, and which is the value.
Interestingly the currency characters are valid as well.
for (int i = Character.MIN_CODE_POINT; i <= Character.MAX_CODE_POINT; i++)
if (Character.isJavaIdentifierStart(i) && !Character.isAlphabetic(i))
System.out.println(i + " : " + (char) i);
prints
36 : $
95 : _
162 : ¢
163 : £
164 : ¤
165 : ¥
1547 : ؋
2546 : ৲
2547 : ৳
2555 : ৻
2801 : ૱
3065 : ௹
3647 : ฿
6107 : ៛
8255 : ‿
8256 : ⁀
8276 : ⁔
8352 : ₠
8353 : ₡
8354 : ₢
8355 : ₣
8356 : ₤
8357 : ₥
8358 : ₦
8359 : ₧
8360 : ₨
8361 : ₩
8362 : ₪
8363 : ₫
8364 : €
8365 : ₭
8366 : ₮
8367 : ₯
8368 : ₰
8369 : ₱
8370 : ₲
8371 : ₳
8372 : ₴
8373 : ₵
8374 : ₶
8375 : ₷
8376 : ₸
8377 : ₹
43064 : ꠸
65020 : ﷼
65075 : ︳
65076 : ︴
65101 : ﹍
65102 : ﹎
65103 : ﹏
65129 : ﹩
65284 : ＄
65343 : ＿
65504 : ￠
65505 : ￡
65509 : ￥
65510 : ￦
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